Thermostat turns HVAC on even when I've turned it off

My AC is in need of repair but I’m waiting for parts. To not stress the unit, I’ve turned HVAC off so it won’t try and run the AC. But every few days, I’ll here the compressor outside fire up because it’s decided to turn the AC back on. How can I prevent the thermostat from turning HVAC on when I’ve turned it off? I use the dial control, I go to HVAC and switch from Cool to Off. What else do I need to do?

I’m by no means an expert in on this, but I’d pull the condenser disconnect or even turn off the circuit breaker for the AC. (The safest bet is to turn off the circuit breaker).
Here’s a photo of a generic disconnect… it’s on the wall of the home.

The stat may be an issue also, but pulling the disconnect or turning the circuit breaker OFF, should stop this behavior for now. Good Luck!